Device for inserting pre-wound coils into stator slots

ABSTRACT

The invention relates to a device and a method for the insertion of pre-wound coils into the slots of a stator of a rotary electric machine. The device comprises a cylindrical finger holder having on its periphery an annular series of longitudinal grooves, housing a series of fingers which extend beyond one end of the finger holder to receive the pre-wound coils. At the other end of the cylindrical finger holder opposite that from which the fingers extend is an end portion which is insertable into a stator and is provided with reference means for determining the correct angular orientation of the finger holder and the fingers with respect to the stator slots when the said other end portion of the finger holder is inserted into the interior of a stator. The device further includes means for drawing the finger holder right through the stator, with the said other end portion as the leading end, after this latter has been introduced into the stator, so that the fingers carrying the pre-wound coils are drawn through the stator in the correct angular orientation to effect insertion of the pre-wound coils carried by the fingers into the stator slots.

The present invention relates generally to the production of stators forrotary electric machines, and particularly to a device and a method forinserting pre-wound coils into stator slots.

Devices for performing this operation are known from the prior art,particularly from the prior art specifications which will be discussedbelow; these devices comprise a cylindrical finger holder having on itsperiphery an annular series of longitudinal grooves which receive aseries of longitudinally extending fingers which project beyond one endof the said finger holder to receive pre-wound coils which are to beinserted into the stator slots. In the following description devices ofthis general type will be referred to as "devices of the specifiedtype".

A device of the specified type is described and illustrated in U.S. Pat.No. 3,324,536 in the name of HILL. The device forming the subject ofthis patent also includes a tubular external casing surrounding thefingers and provided with threaded holes into which engage screws forlocking the fingers into respective grooves of the finger holder. Astar-shaped stripper member having in its outer periphery a series oflongitudinal grooves is disposed in the space within the annular seriesof fingers, and these longitudinal grooves receive those portions of thesaid fingers which project beyond the finger holder. The stripper memberis displaceable axially with respect to the fingers. A stator into whichthe pre-wound coils are to be inserted has a plurality of axial statorslots defined by an annular series of radially extending stator teeth.The stator is mounted coaxially with respect to the annular series offingers adjacent the free end of these latter in such a way that theradially inner faces of the stator teeth (which are separated from oneanother by the stator slots in which the coil is to be inserted) are incontact with the other faces of the fingers. The stripper is thendisplaced axially along the fingers towards their free ends so as toforce the coils to slide along the fingers until they have been insertedinto the stator slots. As described in the above mentioned U.S. Pat. No.3,324,536 the coil inserting device further includes a series ofauxiliary fingers constituting wedge guide members which are arranged inan annular series disposed about the series of fingers which arereceived in the grooves of the finger holder. The wedge guide membersserve for guiding wedge-shape insulating elements into the stator slotsduring operation of the device. The wedge guide members are shorter thanthe fingers disposed in the grooves of the finger holder so that in thepositions adopted when the device is ready for operation the free endsof the wedge guide members are located at a certain distance from thefree ends of the fingers received in the grooves of the finger holder.In this way it is possible to fit a stator over the free ends of thefingers which are lodged in the grooves of the finger holder and to restthe stator itself on the free ends of the wedge guide members, with thestator abutting the ends of the wedge guide members.

This device has a number of disadvantages. First of all, the device hasto set up for the insertion of pre-wound coils into the stator slots ofa stator having a given axial length, and should it become necessary toutilise the device for the insertion of coils into a stator having adifferent axial length from that for which the apparatus is set up it isnecessary to release locking screws which retain the fingers in thefinger holder and axially displace these fingers with respect to thefinger holder whereby to adjust the distance between the free ends ofthese fingers and the free ends of the auxiliary fingers constitutingthe wedge guide members.

Another disadvantage of known devices of the specified type lies in thefact that, during the actual insertion of pre-wound coils into thestator slots, the wires of each coil are pressed into a cluster in theapertures between the fingers thereby giving rise to friction betweenthe wires of each coil and the surfaces of the fingers in contact withthem. This friction can become so great as to render the insertion ofthe coils impossible, and can further cause the pinching of the wires tothe extent that the insulating lacquer becomes damaged. Even withoutsuch extreme effects the stripper has to apply a significant force (from2000 to 4000 Kg.) in order to effect insertion, and this carries with itthe ever-present risk of damage to the wires of the coils.

Finally, in the known device described in the above mentioned U.S.Patent the positioning of the stator over the free ends of the fingerslodged on the grooves of the finger holder must be effected withparticular precision and accuracy. The outer surface of each finger(which is intended to come into contact with the radially inner face ofone of the stator teeth) has, in fact, two longitudinal lateral ridgesintended to engage respectively into two adjacent stator slots separatedby a stator tooth which itself engages in the longitudinal recess in thefinger defined by these axial ridges. Because these ridges have arelatively small thickness they are therefore very delicate, and it isnecessary to take great care whilst fitting the stator onto the fingersto ensure that it is perfectly fitted and to avoid causing breakage ofthese ridges. This problem is particularly acute in the case where thedevice is to be used in an automatic stator-assembling machine.

Various different arrangements have been tried in an attempt to obviatethe above mentioned disadvantages. For example, in order to obtain asimple and rapid adjustment of the device, to accommodate changes in theaxial length of the stators being used, it has been proposed to fix theauxiliary fingers constituting the wedge guide means to the tubularouter casing described above and to provide means for axially displacingthis tubular outer casing with respect to the finger holder whichcarries the fingers intended to receive the stator. In this way anydesired variation in the distance between the free ends of the fingerslodged in the finger holder and the free ends of the auxiliary fingersconstituting the wedge guide means can be obtained simply by effecting asuitable axial displacement of the tubular outer casing with respect tothe finger holder. However, the range of adjustment which can beobtained in this way is relatively limited, being equal only to about athird of the axial length of the finger holder itself.

Other arrangements have been proposed specifically for the purpose ofavoiding the pinching of the pre-wound coils between the fingers duringinsertion of the coils into the stator slots. For example U.S. Pat. No.3,559,268 in the name Droll (corresponding to German Pat. No. 1 918 485)relates to a device of the specified type including a stripper similarto that described above, and a series of fingers received in the groovesof the stripper. Some of these fingers are fixed to the stripper ratherthan to the finger holder in such a way as to be movable axially with itduring the insertion of coils into the stator slots, whereby to reducethe friction between the wires of the coils and at least some of theadjacent fingers. In this device, however, the fingers which are fixedto the stripper are subjected to a notable wear of their axial ridgesbecause of the transverse thrust which is exerted on them in use.

The problem of avoiding the above mentioned phenomenon of pinching isalso considered in Italian Patent Application Ser. No. 69440-A/78 filedOct. 24, 1978 and in the corresponding U.S. Patent Application Ser. No.77,529 filed Sept. 27, 1979 by the same Applicant. In the devicedescribed in these specifications several of the fingers intended toreceive a coil are free to slide axially both with respect to thestripper and with respect to the finger holder such that these fingersmove with the stripper only if the frictional forces are sufficientlyhigh for the phenomenon of pinching to occur, whilst they remain firmlyconnected to the finger holder for movement therewith otherwise. In sucha device the frictional forces which are exerted on the "free" fingersare utilised for causing the axial movement of these fingers.

In the known devices described above, although, to some extent at least,the problem of pinching of the pre-wound coil is overcome, the problemof the adaptation of the device to accommodate stators having adifferent axial length remains.

There are also known prior art devices in which a centering tool is usedfor the purpose of avoiding the breakage of the longitudinal ridges ofthe fingers when mounting a stator on these latter. Such a centeringtool is constituted by a cylindrical body which has a diametercorresponding to the inner diameter of the stator. The tool has a handleand further includes a series of radial reference fingers intended to beinserted into the stator slots. Before the stator is mounted on the freeend of the fingers of the insertion device, an end portion of thecentring tool is fitted into the inner space between the fingersadjacent the free end of these. The remaining portion of the tool,carrying the said reference fingers, remains projecting beyond the freeends of the fingers. The stator is therefore mounted onto the fingers ofthe coil insertion device by making it first pass over the saidprojecting portion of the tool. The engagement of the radial referencefingers of the tool onto the slots of the stator allows the correctangular orientation of the stator with respect to the annular series offingers of the coil insertion device before the stator itself comes intocontact with these latter. In this way a rapid and precise mounting ofthe stator can be obtained, whilst at the same time avoiding breakage ofthe longitudinal ridges of the fingers. Although the use of a centeringtool has certain advantages the mounting of a stator by means of acentering tool is extremely difficult if the stator already has a layerof coils fitted thereon. In this case, in fact, because part of each ofthe coils already fitted extends axially beyond one end of the stator,and also projects into the interior space of the stator itself, it isnecessary, before introducing the stator, to arrange the coils in thecorrect manner in order to ensure that there are no parts of these whichcan interfere with the centring tool. This is time consuming andrequires manual intervention.

The present invention seeks, therefore, to provide a device for theinsertion of pre-wound coils into stator slots in stators for electricalmachines, by means of which all the advantages obtainable separately bymeans of the known devices described above can be obtained, whilst atthe same time all the above mentioned disadvantages of the prior art canbe avoided.

Therefore, according to one aspect of the present invention, there isprovided a device for the insertion of pre-wound coils into the slots ofa stator of a rotary electric machine, of the type comprising: acylindrical finger holder having on its periphery an annular series oflongitudinal grooves and a series of fingers fixedly located in thegrooves of the said finger holder and extending beyond one end of thesaid finger holder to receive thereon the pre-wound coils, characterisedin that the other end of the said cylindrical finger holder oppposite tothe said one end from which the fingers project, has an end portionextending axially beyond the fingers, in that the said other end portionis provided with angular orientation reference means for cooperatingwith the slots of a stator whereby to obtain the correct angularorientation of the annular series of fingers with respect to the slotsof the stator when the said other end portion of the finger holder isinserted into a stator, and in that there are provided means foreffecting axial displacement of the said finger holder, with the saidother end portion as the leading end, after this latter has beenintroduced into a stator, whereby to cause the said fingers to be drawnthrough the stator by the finger holder and to draw pre-wound coilscarried thereon into the slots of the stator. The said reference meansmay be formed directly on the finger holder itself, although in apreferred embodiment there is provided an annular member surrounding thefinger holder and carrying the said reference means.

With such a device there is no constraint on the axial length of thestator which can be used with the device, and because of the referencemeans with which the end portion of the finger holder is provided thereis no necessity for a separate centering tool in order to obtain thecorrect angular orientation of the stator and the finger holder in orderto ensure proper alignment with the stator slots. This makes the deviceaccording to the invention particularly suitable to be used in automaticmachines.

Moreover, the device according to the invention is not subject to theabove described disadvantage due to pinching of the wires of the coils.In particular, in order for the fingers to draw the coils into thestator slots the friction which is created between the wires of the coiland the fingers themselves is exploited. This friction is rather lessthan that which occurs in the known devices and it allows theutilisation of a very modest coil-insertion force, not greater than 400Kg., for the displacement of the finger holder.

The device forming the subject of the present invention isconstructively simple and of low cost, and embodiments of the inventioncan be made both economically and simply.

According to a second aspect of the present invention there is provideda method for the insertion of pre-wound coils into the slots of a statorof a rotary electric machine using a cylindrical finger holder having onits periphery a series of longitudinal grooves and an annular series offingers fixed in the grooves of the said finger holder and extendingbeyond one end of the said finger holder to receive the said pre-woundcoils, characterised in that the said method comprises the steps of:inserting into a stator an end portion of the cylindrical finger holderopposite the end thereof from which the said fingers project, angularlyorienting the finger holder in order to align pre-wound coils carried bythe fingers thereof with the stator slots, and effecting an axialdisplacement of the said finger holder through the stator with the saidend portion as the leading end, whereby to cause the said fingers todraw the pre-wound coils carried thereon through the stator and toinsert them into the slots of the stator.

As distinct from all known methods, in which insertion of the pre-woundcoil into the grooves of the stator is effected by a displacement of thecoil towards the free ends of the fingers on which these coils aredisposed, in the method according to the present invention the insertionof the coils into the grooves of the stator is obtained by causing adisplacement of the coils in the opposite direction, away from the freeends of the fingers on which the coils are disposed. In other words, thecoils are "drawn" rather than "pushed" into the grooves of the stator.In order that the coils be drawn by the fingers the friction which iscreated between the wires of the coil and the fingers in contact withthese is exploited. It is thus possible, as already mentioned, toutilise only quite modest forces (in any case not greater than 400 Kg)for effecting the displacement of the finger holder.

Various embodiments of the present invention will now be moreparticularly described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is an axial sectional view of part of one embodiment of a deviceaccording to the present invention;

FIG. 2 is an axial sectional view of a part of the device illustrated inFIG. 1, in a different operating position;

FIG. 3 is a sectional view taken on the line III--III of FIG. 1;

FIG. 4 is a partial sectional view taken on the line III--III of FIG. 1with the device in a different operating position;

FIGS. 5, 6 and 7 illustrate three different variations of a component ofthe device illustrated in FIG. 1;

FIG. 8 illustrates a further embodiment of the device according to theinvention;

FIG. 9 is a side view of an automatic machine utilising the device ofFIG. 8; and

FIGS. 10 and 11 are, respectively, a plan view and a side view ofanother machine utilising the device illustrated in FIG. 8.

Referring now to the drawings, there is shown a stator 1 for a rotaryelectric machine in the form of an annular body having on its innersurface a series of longitudinal slots 2 (see FIG. 4) intended toreceive the coils constituting the winding of the stator. The slots 2are defined between adjacent pairs of radially inwardly projectingstator teeth 2a.

A device for the insertion of pre-wound coils into the slots 2 of thestator 1 is generally indicated 3; the device 3 comprises a cylindricalfinger holder 4 having on its radial outer cylindrical wall an annularseries of longitudinal grooves 5, two diametrically opposite grooves ofwhich are visible in FIGS. 1 and 2. Lodged within the grooves 5 of thefinger holder 4 is an annular series of fingers 6 (see also FIG. 4). Thefingers 6 are fixed to the finger holder 4 by means of screws 7 as canbest be seen in FIG. 1.

The fingers 6 extend beyond one end of the finger holder 4 to receive,in a manner analogous to that described and illustrated in U.S. Pat. No.3,324,536, the pre-wound coils 8 which are to be inserted into the slots2 of the stator 1. The finger holder 4 has a cylindrical cavity 9 with acircumferential groove 10 located approximately mid-way along it.

A hollow shaft 11 in the form of a tubular element projecting into thecavity 9 is slidable with respect to the finger holder 4 but can befixed axially thereto by means of a plunger member 12 mounted slidablywithin the shaft 11 and operable to cause a series of balls 13 lodged inrespective radial holes 14 in the wall of the tubular shaft 11 to becomeurged radially outwardly to engage in the groove 10 to effect axialfixing. The plunger member 12 has a portion of reduced diameter 15. Whenthis portion is located adjacent the radial holes 14 the tubular shaft11 is free to slide axially with respect to the finger holder 4 becausethe balls can move radially inwardly. When the plunger element 12 isdisplaced axially with respect to the tubular shaft 11 in such a way asto move the portion of reduced diameter 15 out of axial alignment withthe radial holes 14, the balls 13 are pressed into engagement in thegroove 10 whereby to join the tubular shaft 11 and the finger holder 4rigidly together in respect of axial displacements and axial forces.

The finger holder 4 has an end portion 16 which extends axially beyondthe fingers 6 at the end opposite that end of the finger holder 4 fromwhich the fingers 6 project. On this end portion 16 of the finger holder4 there is fixed an annular element 17 having an outer diametercorresponding to the inner diameter of the stator 1. This annularelement is provided with a set of three reference keys 18 angularlyequidistantly spaced from one another, projecting from the periphery ofthe annular element 17 and able to be inserted in the manner illustratedin FIG. 3 into the correspondingly angularly spaced slots 2 of thestator 1.

The operation of the device described above is as follows;

Before proceeding to mount the unit comprising the finger holder 4 andthe fingers 6 onto the stator 1, the pre-wound coils 8 are disposed onthe fingers 6 in the pre-established pattern according to therequirements of the stator. At this point the end portion 16 of thefinger holder 4 carrying the annular element 17 is inserted into thestator 1 causing the engagement of the three reference keys 18 in threeof the slots 2 of the stator 1. The unit comprising the finger holder 4and the fingers 6 is thus inserted into the interior of the stator 1from above until it is carried into the position illustrated in FIG. 1,by means of a displacement which, with reference to the orientation asviewed in FIG. 1, takes place from above downwardly.

The engagement of the reference keys 18 of the annular element 17 intothe slots 2 of the stator 1 ensures the correct angular orientation ofthe annular series of fingers 6 with respect to the slots 2 of thestator 1.

Once the annular element 17 has been introduced into the interior of thestator 1, the tubular shaft 11 is introduced up from below into thecavity 9 of the finger holder 4 and fixed to this finger holder bydisplacing the plunger member 12 in such a way as to cause theengagement of the balls 13, by moving outwardly, in the circumferentialgroove 10 of the cavity 9. With the tubular shaft 11 now fixed to thefinger holder 4, axial displacement of the tubular shaft 11 downwardly,as viewed in FIG. 1, takes place so as to force the fingers 6 and thepre-wound coil 8 disposed on them to be drawn through the stator 1. Thesection illustrated in FIG. 4 is contained in the plane indicated withthe line III--III in FIG. 1 and corresponds to that stage of thedownward displacement of the finger holder 4 during which the free endsof the fingers 6 are in contact with the inner surface of the stator.The downward movement of the finger holder 4 continues until the unitcomprising the finger holder 4 and the fingers 6 is carried into theposition illustrated in FIG. 2. When the unit reaches this position thecoils 8 are by now inserted in the corresponding slots 2 of thestator 1. During insertion the coils 8 follow the fingers 6 because ofthe frictional force exerted between the wires of the coil and thefingers; this frictional force is, however, not high.

The fingers 6 may have one of various different forms in transversesection, as is illustrated in for example FIGS. 5 to 7. In each case,however, each finger has two longitudinal ridge portions 6a at eitherside, which are operable to become engaged (see FIG. 4) into theadjacent pair of slots 2 of the stator 1 which delimits the innersurface portion of the stator tooth 2a with the radially inner surfaceof which each finger 6 comes into contact.

The presence of the annular element 17 having the reference keys 18ensures that the proper angular orientation of the annular series offingers 6 with respect to the slots 2 of the stator 1 is obtained,whereby to avoid the breakage of the small ridges 6a of the fingersduring the insertion of the fingers into the stator 1. This is of vitalimportance because the first part of each finger which comes intocontact with the stator is that end fixed to the finger holder. There isthus no resilience in the mounting of the fingers and any angularmisalignment would almost certainly lead to breakage of these ridges.

The walls of each slot 2 of the stator 1 are, of course, covered with aninsulating material 19 (see FIG. 3).

If it should be necessary to introduce into the slots 2 of the stator 1wedge-shape insulating elements (sometimes called "keys" by thoseskilled in the art) for the end closure of the stator slots and toretain the coils, this operation can be performed separately, by knownmeans, or else can be performed contemporaneously with the operation ofinsertion of the coils by utilising the device illustrated in FIG. 8.

The parts of the device illustrated in FIG. 8 which are in common withthe devices illustrated in FIG. 1 are indicated with the same referencenumerals as in FIG. 1.

Referring now to FIG. 8, the device as a whole is indicated generallywith the reference numeral 20; it comprises a device 3, identical tothat illustrated in FIG. 1, for the insertion of pre-wound coils intothe slots 2 of a stator 1, and a device 21 of a type known per se, forthe introduction of wedges or closure keys into the slots 2 of thestator 1.

The wedge insertion device 21 comprises an outer tubular casing 22within which there is located an annular series of auxiliary fingers 23which surround the annular series of fingers 6. The auxiliary fingers23, herein-after referred to as wedge guide members, are provided withgrooves 24 in their side faces for the guidance of closure keys orwedges 25 (referred to in the abovementioned U.S. Pat. No. 3,324,536 as"bore wedges") into the slots 2 of the stator 1. The outer casing 22 andthe auxiliary fingers 23 serve the same function as that of thecorresponding elements forming part of the device illustrated in U.S.Pat. No. 3,324,536. A series of wedge pusher elements 26 are providedfor pushing the wedges or keys 25 along the grooves 24 of the wedgeguide members 23 until they have been inserted into the stator slots.The device 21, in the embodiment illustrated by way of example in FIG.8, also comprises an element 27, axially displaceable by means of acontrol shaft 27a, which is entirely similar to the stripper illustratedin the above-mentioned U.S. Patent. The element 27 is provided aroundits periphery with an annular series of longitudinal grooves 28 able toreceive the fingers 6. In the case of the device of FIG. 8 the element27 is not used as a stripper, but rather as an abutment elementcontacting the back of the wedges 25 during the insertion of thesewedges into the stator slots.

The operation of the device illustrated in FIG. 8 is as follows:

First, the unit comprising the finger holder 4 and the fingers 6 isinserted from above, downwardly into the stator 1 in a manner analogousto that described for the device illustrated in FIG. 1. The tubularshaft 11 is then inserted up from below into the interior 9 of thefinger holder 4 and locked into axial engagement with the finger holderby means of the balls 13 by acting on the plunger element 12.

At this point the device 21 is lowered from above onto the stator 1until the free ends of the auxiliary fingers constituting the wedgeguide members 23 have been carried into the position where they rest onthe upper surface of the stator 1 engaging against the radially outerfaces of the fingers 6 of the device. The wedge pusher elements 26 andthe element 27 are then axially displaced downwardly whilst, at the sametime, the downward axial displacement of the tubular element 11 is alsoeffected. In this way both the pre-wound coils 8 and the closure keys orwedges 25 are inserted into the stator slots.

It is possible to provide a spacer element fixed onto the upper end ofthe finger holder 4 so that the element 27 comes into contact with itwhen the wedge-insertion device 21 is located in a position ready forthe insertion operation. In this way it is possible to effectdisplacement both of the element 27 and of the finger holder 4 by actingonly on the shaft 27a.

FIG. 9 illustrates an automatic machine utilising the coil insertiondevice 20 illustrated in FIG. 8. This machine, which is generallyindicated with the reference numeral 30, is associated with an automaticpallet- type conveyor line 31 (seen in end view) which supplies to theinsertion device a succession of stators 1 into which the pre-woundcoils are to be inserted.

As can be seen in FIG. 9, the machine 30 comprises a base 32 whichsupports two columns 33 connected by a cross-piece 33a. On the columns33 there is mounted, in a vertically slidable manner, a bridge structure34 containing apparatus, of a type known per se, for the preparation ofthe closure keys or wedges intended to be inserted into the slots of thestator. A unit including an assembly of wedge pusher elements 35 fordriving the wedges into the stator is generally indicated 34. Anhydraulic actuator cylinder 36 is provided for effecting thedisplacement of the wedge pusher elements 35. An hydraulic actuatorcylinder of known type, not visible in the drawing, is provided foreffecting the vertical displacement of the bridge structure 34 up anddown the columns 33. From the unit 34 there projects downwardly a device21, similar to that described with reference to FIG. 8, for theintroduction of the wedges into the stator slots.

The shaft intended to control the axial displacement of the device 3 forobtaining the insertion of the coils into the interior space of thestator is indicated 37. The shaft 37 is fixed to a support element 38which is guided in a vertically slidable manner with respect to the base32 and is connected to this latter by means of a control cylinder 39. Achain conveyor 40 is utilised for the recovery of the insertion devicesafter these have been utilised since, obviously, these pass rightthrough the stator starting from above and ending below, and require tobe returned to a position above the working station for subsequentre-use.

The operation of the machine illustrated in FIG. 9 is as follows:

When the pallet conveyor 31 carries a stator 1 into position in theworking station of the machine, the device 3 including the finger holder4 and the fingers 6 carrying the pre-wound coil has already beenpreliminarily positioned partly inserted into the interior of thisstator in the manner which has been described above. At this point thecylinder 39 is controlled to retract in such a way as to raise the shaft37 (which corresponds to the shaft indicated with the reference numeral11 in FIG. 8) and to insert it into the cavity 9 of the finger holder 4of the device 3. Contemporaneously the bridge structure 34 is lowered tocarry the device 21, and in particular the auxiliary fingers 23constituting the wedge guide means for the insertion of the wedges, downinto the position illustrated in FIG. 8. The insertion of the pre-woundcoils 8 into the hollow interior of the stator 1 is then obtained byextending the actuator cylinder 39 so as to displace the finger holder 4of the device 3 downwardly to draw the fingers 6 through the stator 1.At the same time the actuator of the unit 35 is operated to drive thewedges into the stator slots as described in relation to FIG. 8.

When the shaft 37 has been lowered by extension of the actuator 32 tothe position illustrated in FIG. 9, the unit comprising the fingerholder 4 and the fingers 6, which has passed right through the stator 1,is recovered by the chain conveyor 40, so that the shaft 37 is now freeto become inserted into the next finger holder forming part of thecoil-insertion device which is next fed to the machine. At the same timethe bridge structure 34 returns to its raised position.

FIGS. 10 and 11 are, respectively, a plan view and a side view ofanother machine utilising the device illustrated in FIG. 8.

The machine illustrated in these Figures is associated with an automaticpallet conveyor line, as can be seen in FIG. 10, although it can be usedseparately from such a conveyor if desired. The machine comprises a base41 on which there are supported four winding heads 42 to 45 of a typeknown per se for the formation of coils on the fingers of the insertiondevices. The machine is associated with an automatic pallet transportline 46 which feeds stators 1 in succession to a work station 47 wherethey receive the pre-wound coils formed by the winding heads 42 to 45.On the base 41 there are mounted two columns 48 connected by across-piece 49 (only part of which is shown in FIG. 11) and supporting,in a slidable manner, a bridge structure 50 containing apparatus, of atype known per se, for the preparation of the wedges intended to beinserted as closure keys into the stator slots. In this case too, thereis provided a set of wedge pusher elements 51 for driving the wedgesalong the auxiliary fingers 23 constituting the wedge guide means of thewedge-insertion device 21 carried below the bridge structure 50, and anhydraulic actuator cylinder 52 for effecting axial displacement of thewedge pusher elements 51.

In a manner similar to that described in relation to FIG. 9, there isprovided a lower actuator cylinder 53 for effecting axial displacementof an element 54 which corresponds to the hollow shaft 11 of FIG. 1 andwhich is engageable from below into the finger holder of the coilinsertion device in order to draw it through a stator to effectinsertion of the pre-wound coils into the stator slots.

The machine is further provided with a horizontal actuator cylinder 55which acts to withdraw the coil insertion devices laterally after thesehave been utilised for the insertion of the coils into the stator, andwith an associated vertical actuator cylinder for carrying them up intoa position where they can be taken up by the winding heads for asubsequent cycle of operations.

In addition, each of the two columns 48 is provided with a respectivesupport 57 on which there is mounted, projecting therefrom and rotatableabout a vertical axis, a working arm 58 serving for the transport of theinsertion devices between a position where they can be operated on bythe winding heads and the working station 47 of the machine.

The operation of the machine described above is as follows:

The winding heads 42 to 45 operate to form coils on the fingers 6 of aninsertion device 3 which is located on correspondence with these,according to a pre-established sequence. When the windings formed on thefingers of the insertion device 3 which is located at one of the windingheads have been completed, one of the two working arms 58 carries theinsertion device 3, with the pre-wound coils disposed on it, into theworking region 47 and inserts it, downwardly from above, in the mannerwhich is described above with reference to FIG. 1, into a stator 1 whichhas been fed by the conveyor line 46 into the work station 47. At thesame time the cylinder 55 is retracted to withdraw the insertion devicewhich was last utilised, and following the completion of this retractionthe cylinder 56 is extended to carry this insertion device up to thefirst winding head. At this point the actuator cylinder 53 is driven toextend to cause the element 54 on the finger holder of the device 3 toengage, whilst, at the same time, the bridge structure 50 is lowered insuch a way as to carry the device 21 and the auxiliary fingers 23 intothe position illustrated in FIG. 8. From this position the insertionphase is then performed in a manner entirely similar to that which isdescribed above with reference to FIG. 9. Once the insertion device hasbeen utilised, the cylinders 55 and 56 carry it back into a positionadjacent one of the winding heads ready to perform another cycle ofoperations.

What is claimed is:
 1. In a device for the insertion of pre-wound coilsinto the slots of a stator of a rotary electric machine, of the typecomprising:a cylindrical finger holder having on its periphery anannular series of longitudinal grooves, and an annular series of fingersaround said finger holder, each finger being received in one of saidgrooves and extending beyond one end of said finger holder to receivethereon said pre-wound coils, the improvement wherein: the other end ofsaid cylindrical finger holder opposite to said one end from which saidfingers project, has an end portion extending axially beyond saidfingers, angular orientation reference means are provided on said otherend portion of said finger holder for cooperating with the slots of astator whereby to obtain the correct angular orientation of said annularseries of fingers with respect to said stator slots when said other endportion of said finger holder is inserted into a stator, and means areprovided for effecting axial displacement of said finger holder, withthe said other end portion as the leading end, after said other endportion has been introduced into a stator, whereby to cause said fingersto be drawn through said stator by said finger holder to draw pre-woundcoils carried on said fingers into said stator slots.
 2. The device ofclaim 1, wherein said angular orientation reference means comprise anannular series of axially extending reference keys carried on saidfinger holder and projecting radially to an extent such as to engageinto circumferentially adjacent slots in said stator.
 3. The device ofclaim 1, wherein said angular orientation reference means comprise anannular series of axially extending reference keys carried on an elementsupported by said finger holder, said reference keys projecting radiallyto an extent such as to engage into circumferentially adjacent slots insaid stator.
 4. The device according to claim 1, wherein saidcylindrical finger holder is a hollow body having a cavity therein andsaid means for effecting axial displacement of said finger holderincludes:a shaft insertable into said cavity of said finger holder, andmeans for selectively fixing said shaft to said hollow body.
 5. Thedevice of claim 4, wherein the interior surface of said cavity of saidfinger holder is formed with a circumferential groove and said shaft isconstituted by a tubular element,means defining a plurality of radialholes in said tubular element, a plurality of balls each housed in arespective said radial hole, and an axially displaceable engagementmember operating on said balls to engage them into said groove when saidshaft is axially positioned with said radial holes thereof axiallyaligned with said groove whereby to connect said finger holder and saidshaft for axial movement together.
 6. The device of claim 1, whereinthere are further provided means for inserting insulating wedge elementsinto said stator slots for closure of the ends of said stator slots. 7.The device of claim 6, wherein said wedge element inserting meanscomprises:an outer tubular casing having a first end facing the end ofsaid finger holder from which said fingers project, an annular series ofauxiliary fingers housed in said outer tubular casing, said auxiliaryfingers extending axially beyond said first end of said outer tubularcasing, said auxiliary fingers being disposed around said annular seriesof fingers carried by said finger holder and being shaped with guidemeans for guiding said wedge shape insulating elements, and means foraxially displacing said wedge shape insulating elements with respect tosaid auxiliary fingers towards the free ends of said auxiliary fingersin synchronisation with the movement of said finger holder.
 8. Thedevice of claim 7, wherein said wedge element inserting means furthercomprises a guide element in the form of a cylindrical body having onits periphery a series of longitudinal grooves able to receive saidfingers carried by the said finger holder.